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Autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a rare, but chronic inflammatory disorder of the pancreas. It is caused due to the body’s own defense mechanism attacking the pancreas. They are of two types namely, type I AIP and type II AIP. Type I affects multiple organs along with pancreas while type II affects only the pancreas.

Causes

The exact cause of autoimmune pancreatitis is not known, but it is due to the immune cells attacking your own pancreatic cells, similar to the other autoimmune diseases.

Risk factors

Type I AIP

Gender: The condition is predominant in males when compared to females

Age: Occurs in your 60’s and 70’s

Type II AIP

Gender: The condition is equally likely in both males and females

Age: Occurs in your 40’s and above

Complications

If a timely treatment is not made available for the patient with autoimmune pancreatitis, then the following complications can occur:

Diabetes: In autoimmune pancreatitis, the insulin production is affected due to the damage to the pancreas. This can lead to diabetes, and the patient may require oral anti-diabetic medications or insulin injections. Pancreatic insufficiency: As the ability of the pancreas to produce adequate enzymes is affected in AIP, the patient may have diarrhea, weight loss, vitamin or mineral deficiency and metabolic bone disease.

Pancreatic calcifications or stones formation can occur in the pancreas over time.

The treatments such as long-term steroids used for AIP management also can cause certain complications. However, the life expectancy of the patients treated is normal.

An accurate diagnosis of autoimmune pancreatitis is important as it has similarities with pancreatic cancer. Underdiagnosis can lead to the delay in treatment or a wrong treatment.

Type I AIP

You have type I AIP, if your diagnostic tests shows:

  • One or more masses in the pancreas or occasionally in the other organs
  • Elevated levels of IgG4 (antibodies) in the pancreas or occasionally in the other organs
AIP type II

You have type II AIP, if your diagnostic tests shows:

  • Normal levels of IgG4 (antibodies) in the pancreas or the other organs
  • Granulocyte epithelial lesions in the pancreatic ducts which cause the destruction of the ducts

An endoscopic biopsy has to be done for a definitive diagnosis of type II AIP. During the biopsy, the distinctive appearance of the pancreatic tissue is identified under the microscope which indicates type II AIP.

Before the autoimmune pancreatitis treatment begins, a biliary stent is inserted to drain the bile from the ducts in case if obstructive jaundice is identified.

Steroidal therapy: Autoimmune pancreatitis is highly responsive to steroidal therapy. It regresses or resolves with treatment using steroids. A short course of prednisolone improves the symptoms of AIP. People with type I respond faster to the treatment with steroids compared to those with type II. However, the chances of relapse after the treatment is more in type I.

Steroids also can treat the extrapancreatic manifestations which need continuous monitoring.

Immunosuppressants or immune modulators may be used in case of relapse of AIP which is possible in 30-50% of the patients treated with steroids. As long-term treatment with steroids can lead to serious side effects, immune suppressing agents such as mercaptopurine, azathioprine, mycophenolate, and rituximab are given.

For patients with pancreatic insufficiency, supplementary enzymes are given.

If diabetes has occurred as a complication of AIP, then appropriate anti-diabetic medication will be given.

The signs and symptoms of autoimmune pancreatitis and pancreatic cancer are similar, but the treatments are different for both. Therefore, it is important to distinguish them.

Autoimmune pancreatitis symptoms are usually not evident but include the following in the patients who have symptoms:

  • Yellow skin and eyes (painless jaundice which is the most common presenting symptom)
  • Amber colored urine
  • Nausea, vomiting
  • Weakness and fatigue
  • Chronic and recurrent pain the abdomen
  • Pain in the middle part of your back
  • Pale stools or stools that float
  • Bloating and loss of appetite
  • Unexplained weight loss
  • Enlarged pancreas, which is difficult to differentiate from pancreatic cancer
  • Strictures in the pancreatic duct
  • Extrapancreatic manifestations such as enlargement of salivary glands and lymph nodes, scars in the bile duct, kidney diseases and liver inflammation